cel-expr/cel-spec resource

Health v2 · maintenance only

Adoption not part of the score

3954 stars · 303 forks observed · 2026-08-28

What it is AI-extracted, prompt v1, taxonomy v1, 2026-08-29, confidence not recorded

The specification and canonical protobuf binary representation for the Common Expression Language (CEL), a fast, non-Turing-complete expression language designed to be embedded in applications. This repo defines the language semantics, AST proto definitions, and conformance tooling rather than providing a runtime implementation itself.

Use cases

• evaluate safe user-supplied expressions in my api
• write authorization policy rules for requests
• add validation constraints to protobuf messages
• embed an expression evaluator in my application
• implement a CEL interpreter in another language
• share expression semantics across services and languages

When to choose

• you need the authoritative language spec or canonical proto definitions to build or verify a CEL implementation
• you want a safe, fast, non-Turing-complete expression language for policies, filters, or validation
• you need expression interoperability across languages and platforms

When to avoid

• you need an actual CEL parser/evaluator runtime - use a language implementation like cel-go, cel-cpp, or cel-python instead
• you need a general-purpose, Turing-complete scripting language

Facets

learning-resource · maturity stable

programming-language parser serialization authorization programming-languages security developer-tools apis cross-platform expression-language specification policy-engine protobuf cel

Member repositories

For agents

markdown · JSON · MCP: product_card(name="cel-expr/cel-spec")